Various fittings have been heretofore proposed for tensioning and untensioning a sailboat stay, particularly a backstay. It is desirable to untension a backstay when a smaller type sailboat is to be hoisted out of the water onto a trailer or cradle. Additionally when sailing off the wind, it is desirable to untension the backstay so as to increase the efficiency of the sails while running. When the sail boat again heads towards the wind, it is essential that the backstay be retensioned quickly. Heretofore proposed quick-release fittings for sailboat stays have generally been bulky and heavy, both features being most undesirable in a sailboat fitting, especially where the sailboat is of the racing type.